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    High-Frequency Magnetics

    D22.12 - An Improved Analytical Methodology for High-Frequency Planar Transformer Design in LLC Converters

    Thursday, March 26, 2026
    12:00 PM - 1:45 PM CT
    Location: Poster 11
    Magnetic design is a critical step in power converter development. The conventional area product method, commonly used for inductors and transformers, assumes constant peak flux density (Bm) and current density, often leading to suboptimal designs. To address this, an improved methodology is proposed for high-frequency transformers, where total magnetic loss (core and copper) is expressed as a function of Bm and area product (Ap), which serve as optimization variables. By incorporating design constraints such as maximum allowable power density and thermal limits, the proposed approach minimizes the total magnetic loss while simultaneously ensuring the smallest feasible core size. The methodology is validated through the design of a transformer for a 120 W, 48 V–12 V LLC converter operating at 1 MHz using N87 ferrite material. Finite-element simulations in ANSYS further confirm the accuracy of the design methodology. Experimental results demonstrate the effectiveness of the proposed transformer design in achieving high efficiency for the fabricated LLC converter.